GRAND RAPIDS, MI -- Though it may not have the state's wealthiest neighborhood, Grand Rapids does have one of its fastest-growing in terms of average individual income.

A Grand Rapids ZIP code, 49503, topped the list of areas with the steepest increase to individual income reported by taxpayers between 2014 and 2015, according to data from the Internal Revenue Service.

Average income in the ZIP code, which includes downtown Grand Rapids, increased by 31.8 percent between 2014 and 2015 filings, the data shows. The average income reported in 2015 was $93,995.75.

That average income level ranks 49503 relatively low on the list of ZIP codes statewide, behind 46 others with higher average incomes in 2015 -- including Kent County ZIP codes of 49506 (East Grand Rapids), 49546 (Cascade) and 49301 (Ada). Leading the list of wealthiest ZIP codes in Michigan were five from Oakland County including Bloomfield Hills' 48304, which topped the list with an average income of $304,637.96.

But no area of Michigan included in the IRS data showed more growth than the central Grand Rapids ZIP code. The next highest percent change was seen in Lansing's 48933 ZIP code (24.4 percent) and Paradise's 49768 ZIP code (23.6 percent).

Three caveats on the IRS data: Average income can be skewed by high-income households, numbers are based on a sampling of returns and ZIP codes with fewer than 100 returns are not included. But the list did include all 56 ZIP codes in Michigan that have an average income of $90,000 or higher.

The impact of high-income households on the average reported by the IRS can be seen in the contrast with U.S. Census figures for the 49503 ZIP code. The area has a median household income of $35,816 and a mean household income of $49,768, according to Census estimates. The Census estimates show about 33 percent of residents in 49503 fall below the poverty level.

Here is a searchable database with data for every ZIP code in Michigan in which the IRS reported data for individual incomes:

You can search the database by county, community or the ZIP code itself.